The specific purpose of this research is to identify the neuroendocrine processes underlying the onset of behavioral estrus in the intact female prairie vole. The female prairie role requires pheromonal and tactile stimulation from male voles for the induction of behavioral estrus. In addition, females require copulatory stimuli for ovulation to occur. Because of this unique pattern of reproduction, the prairie vole provides a useful model for studying the influences of social stimuli on female neuroendocrine function. In general, emphasis will be placed on the biochemical events initiated in naive female voles exposed to male-related stimuli. Of specific interest are the correlations between the intensity of the male stimulus and the pattern of estrogen binding in neural tissues. Studies will also focus on the interactions between the stimulatory effects of the male and the suppressive effects other female voles have on the maturation process. These studies will include investigations of the initial olfactory responses to both male and female stimuli and the ensuing neuroendocrine changes. The results of this research will permit a better understanding of the mechanisms by which social stimuli may influence brain function as well as the behavioral effects of reproductive hormones which are widely used in medicine.